Purification Unit Research Articles

Assessment of the Polluting Status of Sludge from a Physicochemical Water Purification Unit and Their Impacts on the Soil: Case of the Yato Station (Littoral-Cameroon)

The Yato physicochemical water purification station is located in Dibombari District Council in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate, through the quantification of the concentrations of Trace Metal Elements (TMEs), the polluting status of the sludge from this drinking water production station and their impacts on the soil. To achieve this objective, mixed samples of sludge from sludge treatment ponds (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of Code of Good Practice No. 2) and samples of sludge from primary settling basins (taken in transparent bottles in polyethylene terephthalate of 1.5L) were analysed. Likewise, three soil wells were carried out and soil samples were taken on two levels of alteration then sent to the laboratory where physicochemical and TME analyses were carried out. The characteristics of the samples that were analysed are: particle size, texture (sand, silt, clay), physiochemistry (pH, electrical conductivity, temperature, phosphorus, nitrogen) and TME (chromium, copper, zinc, manganese). The results obtained show that the polluting status of the sludge from the Yato station is proven because their pollution index by heavy metals is greater than 1. The pollution index greater than 1 in the sludge from the treatment basins is due to the strong concentrations of TME originating from the accumulation of waste of all kinds in this location. Overall, TME concentrations in soils decrease for the most part from the surface towards depth. All the TMEs studied (Zn, Mn, Cu, Cr) are present in all horizons. There is multiple contamination of sludge by TMEs because their pollution index is greater than 1 (IP>1). Although the sludge pollution indices are greater than 1, those of the different horizons are much lower than 1. Thus, since the TMEs decrease with depth, the subsurface horizons would be less affected by the pollutants contained in the station sludge. marking a real pollution of the surface layers.

Coagulation as an effective method for cyanobacterial bloom control: A review.

Eutrophication, the over-enrichment with nutrients, for example, nitrogen and phosphorus, of ponds, reservoirs and lakes, is an urgent water quality issue. The most notorious symptom of eutrophication is a massive proliferation of cyanobacteria, which cause aquatic organism death, impair ecosystem and harm human health. The method considered to be most effective to counteract eutrophication is to reduce external nutrient inputs. However, merely controlling external nutrient load is insufficient to mitigate eutrophication. Consequently, a rapid diminishing of cyanobacterial blooms is relied on in-lake intervention, which may encompass a great variety of different approaches. Coagulation/flocculation is the most used and important water purification unit. Since cyanobacterial cells generally carry negative charges, coagulants are added to water to neutralize the negative charges on the surface of cyanobacteria, causing them to destabilize and precipitate. Most of cyanobacteria and their metabolites can be removed simultaneously. However, when cyanobacterial density is high, sticky secretions distribute outside cells because of the small size of cyanobacteria. The sticky secretions are easily to form complex colloids with coagulants, making it difficult for cyanobacteria to destabilize and resulting in unsatisfactory treatment effects of coagulation on cyanobacteria. Therefore, various coagulants and coagulation methods were developed. In this paper, the focus is on the coagulation of cyanobacteria as a promising tool to manage eutrophication. Basic principles, applications, pros and cons of chemical, physical and biological coagulation are reviewed. In addition, the application of coagulation in water treatment is discussed. It is the aim of this review article to provide a significant reference for large-scale governance of cyanobacterial blooms. PRACTITIONER POINTS: Flocculation was a promising tool for controlling cyanobacteria blooms. Basic principles of four kinds of flocculation methods were elucidated. Flocculant was important in the flocculation process.

Bayesian cell therapy process optimization.

Optimizing complex bioprocesses poses a significant challenge in several fields, particularly in cell therapy manufacturing. The development of customized, closed, and automated processes is crucial for their industrial translation and for addressing large patient populations at a sustainable price. Limited understanding of the underlying biological mechanisms, coupled with highly resource-intensive experimentation, are two contributing factors that make the development of these next-generation processes challenging. Bayesian optimization (BO) is an iterative experimental design methodology that addresses these challenges, but has not been extensively tested in situations that require parallel experimentation with significant experimental variability. In this study, we present an evaluation of noisy, parallel BO for increasing noise levels and parallel batch sizes on two in silico bioprocesses, and compare it to the industry state-of-the-art. As an in vitro showcase, we apply the method to the optimization of a monocyte purification unit operation. The in silico results show that BO significantly outperforms the state-of-the-art, requiring approximately 50% fewer experiments on average. This study highlights the potential of noisy, parallel BO as valuable tool for cell therapy process development and optimization.

Biohydrogen production from solar and wind assisted AF-MEC coupled with MFC, PEM electrolysis of [formula omitted] and [formula omitted] fuel cell for small-scale applications

Small-scale biohydrogen production is a promising option to reduce GHG emissions for a sustainable H2 economy. Thus, solar and wind aided AF-MEC and MFC coupled with the electrolysis of H2O and a H2 fuel cell were developed. The integrated system uses a microwave oven for digestate pretreatment, and solar or wind energy sources to operate the electrical units. The results show that thermal pretreatment of AF digestate facilitated enzymes’ activities, while the highest energy efficiency recorded in MFC was attributed to the use of AF-MEC by-products as feedstock. The generated electricity by MFC in addition to solar or wind energy systems reduced the overall cost by eliminating AF-MEC separation and purification units for biohydrogen recovery. Renewable energy-powered PEMEC produced H2 and O2 and PEMFC generated electricity for the developed system in the absence of wind and sunlight. Energy efficiency >68.6% and H2 selling price <$5/kg which is cheaper than single electrolysis of H2O unit were recorded with a minimal CO2 by-product. By-product CO2 capture is recommended for an increase in electricity production from the MFC unit. In terms of service life and energy required for manufacturing, this developed system for energy conversation and storage outperforms lithium batteries by >10% efficiency.

Techno-economic and environmental assessment of hydrogen production through ammonia decomposition

Hydrogen is one of the potential candidates to replace fossil fuels to meet net zero emissions target. This study reports a detailed techno-economic and environmental assessment of hydrogen production through ammonia decomposition. The case study is based on a multiple catalytic packed bed reactor with intermediate heating system. Aspen plus® and MATLAB® were linked to evaluate economic and environmental impact of the process. The process parameter like furnace temperature, flue gas recirculation, ammonia decomposition temperature, market ammonia supply pressure, ammonia decomposition pressure, hydrogen purification unit's pressure and equivalence ratio, and economic parameters of capital expenditure (CAPEX) and operating expenditure (OPEX) were considered. The overall thermal efficiency of the developed process is found to be 79%. The levelized cost of hydrogen (LCOH) is estimated and found to be 6.05 USD/kg of H2 based on CAPEX and OPEX. A major contribution of up to 62.2% to LCOH comes from the price of feed Ammonia. Based on 25-year plant life with 10% discounted rate the plant is economically viable, with a return on investment of 23.7%, in a payback period of 3.58 years. Global warming potential of the process is also carried out.

Toward microfluidic continuous-flow and intelligent downstream processing of biopharmaceuticals.

Biopharmaceuticals have emerged as powerful therapeutic agents, revolutionizing the treatment landscape for various diseases, including cancer, infectious diseases, autoimmune and genetic disorders. These biotherapeutics pave the way for precision medicine with their unique and targeted capabilities. The production of high-quality biologics entails intricate manufacturing processes, including cell culture, fermentation, purification, and formulation, necessitating specialized facilities and expertise. These complex processes are subject to rigorous regulatory oversight to evaluate the safety, efficacy, and quality of biotherapeutics prior to clinical approval. Consequently, these drugs undergo extensive purification unit operations to achieve high purity by effectively removing impurities and contaminants. The field of personalized precision medicine necessitates the development of novel and highly efficient technologies. Microfluidic technology addresses unmet needs by enabling precise and compact separation, allowing rapid, integrated and continuous purification modules. Moreover, the integration of intelligent biomanufacturing systems with miniaturized devices presents an opportunity to significantly enhance the robustness of complex downstream processing of biopharmaceuticals, with the benefits of automation and advanced control. This allows seamless data exchange, real-time monitoring, and synchronization of purification steps, leading to improved process efficiency, data management, and decision-making. Integrating autonomous systems into biopharmaceutical purification ensures adherence to regulatory standards, such as good manufacturing practice (GMP), positioning the industry to effectively address emerging market demands for personalized precision nano-medicines. This perspective review will emphasize on the significance, challenges, and prospects associated with the adoption of continuous, integrated, and intelligent methodologies in small-scale downstream processing for various types of biologics. By utilizing microfluidic technology and intelligent systems, purification processes can be enhanced for increased efficiency, cost-effectiveness, and regulatory compliance, shaping the future of biopharmaceutical production and enabling the development of personalized and targeted therapies.

Failure analysis of low-pressure steam superheater in a purification device

For a coal chemical enterprise purification unit in the low-pressure steam superheater in the use of frequent occurrence of heat exchanger tube bundle cracking, to find the cause of failure and ensure the safe and stable continuous operation of the device, the failure analysis work shall be carried out. In this paper, we have examined the cracked heat exchanger tube bundle in terms of macroscopic inspection, material chemical composition analysis, mechanical properties analysis scanning electron microscopy analysis, corrosion product analysis, metallurgical analysis, and many other tests, and also analyzed the internal and external media of the tube bundle, ultimately concluding the main reason for cracking of heat exchanger tube bundle for the alkali stress corrosion cracking. At the same time, to avoid similar problems, we hope that the failure analysis of the use and maintenance, inspection, and testing of the equipment provides a good solution to the failure of the equipment, and provides the best solution to the problem. It is hoped that this failure analysis will provide valuable experience for the use and maintenance of this type of equipment.

Energy, exergy, economic and environmental (4E) analysis of a cryogenic carbon purification unit with membrane for oxyfuel cement plant flue gas

The carbon capture, utilisation and storage (CCUS) process chain is subject to increasing interest, and its overwhelming implementation on the industrial scale appears to be one of the main ways to reduce CO2 emissions. In this context, the optimisation of a CO2 purification process for oxy-combustion cement plant flue gases is proposed. This optimisation is based on a multidimensional study on the energy, exergy, economy, and environmental impacts of the process. The results of the optimisations carried out show that it is more favourable to increase the CO2 recovery above 90%, from an energy, exergy and economic point of view. The analysis of the evolution of the capture cost as a function of the CO2 recovery shows that for a given carbon tax, there is a minimum for the total cost which includes the sum of the carbon tax contributions for the uncaptured CO2 and the capture cost. As the unit uses only electrical energy, the cost and the electricity generation will directly impact the capture cost as well as the overall balance in terms of CO2 avoided. As the electricity price increases from 50 to 250 €/MWh, the CO2 capture cost increases by almost 250%. An analysis of the parameter uncertainties allows to observe their impacts on the results, and to define a standard deviation from the optimised points and show the robustness of these. Considering the technical parametric uncertainties, the standard deviation on the electrical consumption (3.65 kWh/tCO2), CO2 recovery (0.09%) and exergy efficiency (0.92%) is limited.

The effect of heavy metal-containing wastewater sediment on the microanatomical characteristics of the leaves and stem of Salix viminalis L.

A comparative microanatomical study of Salix viminalis L. shoots was performed in order to get an idea of the effect of toxic elements stress on the microanatomical parameters of the shoot (leaves, stem). The examined Salix viminalis L. shoots originated from the Lovász-zug suburban area of Debrecen city, where a sewage settling pond was formerly operated as a secondary biological purification unit. The control Salix triandra x viminalis L. 'Inger' samples originated from the Nyíregyháza experiment with uncontaminated soil. As a result of our research, we can state the following in the case of the leaf samples grown on contaminated soil: the leaf lamina thickness decreased; the extent of the palisade parenchyma decreased; the extent of the intercellular spaced increased inside the spongy parenchyma; the width and the height of the main veins increased; the extent of the collenchyma bordering the main vein increased; the stomatal density increased both in the case of the adaxial and abaxial epidermis; the size of the stomas decreased. In the case of the stem samples, we observed the following: in the case of the samples grown on contaminated soil the extent of the primer cortex increased; the cell wall of the cells building the sclerenchimatic fibers thickened; the number of Ca-oxalate crystal rosettes and sclereids increased; the extent of secondary phloem increased; the lumen of the tracheas in the secondary xylem increased; the average width of the annual rings decreased; the extent of the central stele of the stem increased.

Method for predicting lifetime of ion exchange resin in PWR primary loop based on nuclide distribution measurement

Ion exchange resins are commonly utilized for water treatment in pressurized water reactors' primary loop. These resins have the ability to adsorb radioactive cations present in the primary loop coolant, leading to a purification effect. However, the resin becomes radioactive post-purification and cannot be regenerated, thus requiring regular replacement. As the process of resin replacement exposes personnel to radiation, it is crucial to enhance the resin's utilization. This paper aims to investigate a non-destructive testing method for evaluating the lifetime of resin in pressurized water reactor purification units. It also aims to offer guidance for safe resin replacement. The resin is contained in a column (commonly referred to as ion exchange columns) and consumed from top to bottom, with radioactivity decreasing in intensity from top to bottom. The study utilizes the longitudinal radioactivity distribution characteristics of ionic resins to build a gamma-ray detection system with high resistance to interlayer interference and good longitudinal resolution. In this study, a two-stage resin column was utilized to capture common fission product nuclides and corrosion-activated nuclides, such as 60Co, 137Cs, 54Mn, and 124Sb, from the effluent of a pressurized water reactor. The distribution of these nuclides was measured using this device. The results indicate that the activity levels of 60Co, 137Cs, and 54Mn reached their peak in the column before rapidly declining. The height of the resin layer corresponding to the highest activity level of each nuclide varied, indicating the resin's adsorption selectivity. After processing an additional 10 tons of wastewater, a second measurement was taken which showed that the failure range of the resin expanded downwards as the treated water volume increased. The entire distribution curve of the nuclides within the exchange column also shifted upwards and to the right. By comparing the first and second observations, we discovered that the bottom part of the resin will fail when the activity of the most penetrating nuclide in the wastewater surpasses a specific threshold. This research suggests a novel approach to predicting the lifetime of resin, which generalizes the trend of radionuclide intensity inside the ion exchange column.

Energy efficiency analysis and optimization of a pressurized oxy-fuel circulating fluidized bed combustion system

The commercial application of oxy-fuel combustion technology is limited by energy deduction which is caused by addition of air separation unit (ASU) and carbon dioxide compression and purification unit (CPU). Pressurized circulating fluidized bed (CFB) oxy-fuel combustion technology is one option to improve the net electric generation efficiency. In this research, a series of simulations and optimizations were carried out to analyze the energy efficiency of a pressurized oxy-fuel combustion system. The boiler structure and heat exchange surface arrangement under different pressure were calculated. The cross-sectional area of the furnace and tail flue were both reduced up to 10 % of the original size and the floor space of the boiler was considered to be the lowest at 1.1 MPa. The energy efficiency and exergy analysis were used to explore the influence of pressure on the net efficiency and the optimization potential of system. The net electric generation efficiency reached a maximum value of 24.16 % at 1.1 MPa, which is 5.4 % higher than that at atmospheric pressure. Finally, four parameters, i.e. preheat temperature, oxygen concentration, ASU outlet oxygen purity and CPU compressor outlet pressure, were optimized to improve the system net efficiency to 26.67 %, 29.04 %, 25.87 % and 24.36 %, respectively.

Simulation And Optimization Of Hydrogen Production By Steam Reforming Of Natural Gas

Hydrogen (H2) production through natural gas steam reforming is widely adopted due to its cost-effectiveness and energy efficiency. A simulation and optimization study was performed on an industrial natural gas steam reforming system using Aspen Hysys V12 software to optimize this process. The study focused on optimizing various parameters, including the Reformer Reactor, Water Gas Shift Reactor, and purification units such as the Separator and Pressure Swing Adsorption (PSA). The Reformer and Water Gas Shift reactors were set at 900 °C and 300 °C, respectively, to maximize hydrogen production. Under specific conditions of 5 atm pressure and a steam-to-carbon ratio (S/C) of 2.5, the process achieved a hydrogen production rate of 402.2 kg/h. The treatment zone effectively eliminated ~ 100% of undesirable CO2 and CO gases, with only trace amounts of CH4 and H2 remaining in the waste gases. Additionally, the PSA unit efficiently removed ~ 100% of the water from the separator, ensuring water-free dry gases were sent to the PSA unit. The integration of heating and cooling heat exchange units reduced energy consumption by approximately 51.6%. After the removal of undesired gases in our PSA unit, the production yield for the final product (H2, based on dry gas inlet to PSA) is 77.83%, resulting in 100% pure dry H2. In the waste gas outlet (tail gas) of PSA a composition (22.17%), includes CO, CO, H2O, and CH4. Resulting high-quality hydrogen is well-suited for a wide range of applications, including fuel cells, petroleum refining, natural gas refineries, and petrochemical processes.

Rational amelioration of redox equilibrium by constructing hollow nanotube Co-Mn/TiO2 catalyst to boost simultaneous removal of NO and Hg0

Simultaneous removal of NO and Hg0 in one purification unit is cost-effective, while the conflicting redox environmental requirements remains extremely challenging. Herein, hollow nanotube Co-Mn/TiO2 was elaborately fabricated by reconstructing nanoparticles to ameliorate the redox equilibrium, allowing the catalysts to sustain the excellent synergistic catalytic performance, which delivered more than 98 % NOx conversion with above 95 % N2 selectivity and nearly 100 % Hg0 removal efficiency within 150–240 °C. Abundant oxygen vacancies and strong surface acidity were synchronously generated after the formation of unique hollow nanotube, improving the mobility of oxygen species and facilitating the adsorption and activation of reactants, and the cooperation of oxygen vacancy and surface acidity resulted in superior simultaneous removal activity. Strikingly, in situ DRIFTS and kinetic results revealed that the reaction rate was obviously accelerated on hollow nanotube Co-Mn/TiO2. This study provided new insights toward engineering efficient catalysts for simultaneous removal of NO and Hg0.

Diaminopropane-appended activated carbons for the adsorptive removal of gaseous formaldehyde using a portable indoor air purification unit

It is of significant practical interest to develop high-performance air purifier (AP) for removing carcinogenic volatile organic compounds present ubiquitously in indoor air (e.g., formaldehyde (FA)). In this regard, a portable AP system was designed by loading honeycomb ceramic filters with diaminopropane (DAP)-appended activated carbon (AC). The maximum removal efficiencies (REs) of AP loaded with 10, 20, 30, and 50 %-DAP/AC were 26.2, 28, 88.3, and 89.4 %, respectively, against 5 ppm FA (at 160 L min−1). Hence, the 30 % DAP unit was used mainly in this work. The removal efficiency of 30 %-DAP/AC (160 L min−1), when tested against 2 ppm FA, decreased from 90.3 to 73.2 % with an increase in relative humidity from 0 to 60 %. The performance of the AP unit, when assessed kinetically in terms of the clean air delivery rate (CADR), reached as high as 10.2 L min−1 at the flow rate of 160 L min−1. Isotherm analysis further demonstrated the complex multilayered adsorption behavior of FA. Based on the density functional theory (DFT) simulation, the superiority of DAP/AC for FA adsorption can be attributed to the synergy of covalent (chemisorption) and non-covalent (pore filling and film diffusion) interactions.

Main problems in the operation of metal gas discharge pipes

This paper considers the main problems of operation of metal gas discharge pipes on the example of research and survey work on the examination of building structures of the exhaust tower with three gas discharge trunks 180 m high, flue gas purification unit of the sintering shop of LLP "NDFZ" in Zhambyl region. Analysis of the actual technical condition, considered in this article exhaust tower with three gas discharge shafts, according to the results of the survey, its volume-planning and structural solutions, showed its generally unrepairable, due to the mass of characteristic critical and unacceptable damage to the load-bearing elements of the frame, physical fatigue of materials, significant corrosion wear of metal structures, which will require a significant amount of proposed repair and maintenance work to eliminate them. The conducted complex of researches has shown that the service life of chimneys built before the 1960s and after has practically expired. Repair or reconstruction of chimneys using previously mastered technologies and materials does not solve the issues of reliability improvement. Rational solutions to these problems are periodic technical expertise by highly specialized organizations and implementation on its basis of methods of overhaul of both gas-exhausting trunks and building structures and interface units, wide implementation of which will solve the problem of extending the life of chimneys.

Study of the operating parameters of vibrations of a vibrosieve of the washing liquid purification unit

The object of the research is elastic plates located across the movement of the solution on the vibrosieve. The problem of uniform distribution of material on the surface of the sieve is considered, which is solved with the help of the design proposed in the work. Tensometry was used as a research method with subsequent processing of the results on an elector computer. In the course of the research, an analog-to-digital converter developed and manufactured at the Department of Mechanization of Construction Processes of the National University «Yuri Kondratyuk Poltava Polytechnic» (Ukraine) was used. As well as a computer with a free COM-1 port, «PROGRAM.EXE» software and a spreadsheet editor, strain gauges in the form of strain gauges with two pasted tensor resistors connected by a half-bridge circuit. The paper proposes a fundamentally new scheme of a vibrosieve with additional working bodies in the form of elastic plates located across the movement of the solution on the sieve. The elasticity and mass of the plates are selected in such a way that their oscillations during the operation of the vibrosieve exciter are close to resonance. At the same time, the mode of vibration of the vibrosieve itself is far beyond resonance. As a result, a higher-quality and energy-efficient cleaning of the washing liquid will be obtained. This is due to the fact that the proposed cleaning method has a number of features, in particular, dispersion of drilling fluid over the entire surface of the vibrosieve and maximum loading of the entire working surface of the sieve to avoid dead zones. Thanks to this, it is possible to obtain resonant oscillations. In comparison with known analogs that work in a resonant mode, this provides advantages in the cleaning of drilling mud. The amplitude of oscillations of elastic plates reaches 1.2–1.5 mm, which is significantly greater than the amplitude of oscillations of a vibrating table. In practice, it will be possible to use the proposed fundamentally new scheme of a vibrosieve with additional working bodies in the form of elastic plates that work in a resonant mode, as a way of supplementing vibrosieves that are in use or new when manufactured at manufacturers' factories.

Proposal and comprehensive study of an integrated polygeneration process relying on landfill gas, renewable hydrogen, and binary geothermal cycle

Landfill gas (LFG) is an accessible, inexpensive, and carbon-rich source, and due to its methane content, it can also be used as a fuel. In this paper, a novel polygeneration structure is presented that uses LFG as the input fuel as well as geothermal energy to produce valuable products, including electricity, methanol, freshwater, heating, and cooling. The configuration is made of biogas combustion unit, binary geothermal power plant, cooling water production unit, Kalina power cycle, desalination unit, water electrolysis unit, and methanol synthesis and purification unit. The methanol synthesis unit is modified using a scrubbing column, resulting in recovery of methanol without loss. Aspen HYSYS application is used to model this procedure, and it is examined from a 4E (energy, exergy, economic, and environmental) standpoint. The findings show that a total of55.46% of energyand 77.29% of exergy efficienciesare reached. From the environmental standpoint, it is found that the proposed structure has negative emissions, and its carbon dioxide (CO2) footprint is equal to −0.161 kgCO2/kgprod. In addition, the total CO2 emission of 46,780 kg/h is calculated. Concerning the economic aspect, the cost rate of produced methanol, heating, cooling, and freshwater are found at 0.268 $/kgMeOH, 1.01 $/kgLPS, 0.26 $/kgCW, and 0.7 $/kgFW, respectively. Besides, it is concluded that the methanol production cost rate of this model is comparatively lower than the methods such as power-to-methanol and coke oven gas-to-methanol.

Design studies of a pure hydrogen production plant from biogas

The present paper focus in design studies of a process for pure hydrogen production at decentralized scale. 9000 Nm3/h biogas are proposed as feedstock to the process. The plant includes a biogas-to-biomethane purification unit, a convective reformer equipped with bayonet-type tubes, a Pd-based membrane reactor profiting simultaneous hydrogen extraction and extra hydrogen production via water-gas shift, a combustion chamber and auxiliary units. Three optimization scenarios were considered where the hydrogen production is maximized and reformer and membrane reactors areas are minimized using different weights. All designs are fully thermally integrated aiming self-sustainability in terms of energy. To these ends, the retentate of the membrane reactor and the permeate of the biogas purification unit are both used as fuel to the combustion chamber. Results show the feasibility of operation with an overall thermal efficiency for the process of ca. 77.0–77.5% (based on LHV), comparable with values reported for processes of similar scale.

The power of computational thermochemistry in high-temperature process design and optimization: Part 1 — Unit operations

Industrial process modeling is increasingly accessible through computational chemistry packages. Computational Thermochemistry (CT) is particularly convenient for exploring the behavior of high-temperature processes (e.g., pyrometallurgical unit operations such as calciners, roasters, smelters, converters, and electric arc furnaces) since their operating conditions are mostly dictated by local/global thermodynamic phase equilibria. Under these high-temperature conditions, energy barriers are small and do not limit the kinetics of many chemical reactions. In this context, engineers-in-training must take full advantage of CT to explore and understand current unit operations in high-temperature manufacturing technologies. This work illustrates the strength of computational thermochemistry for high-temperature modeling through four case studies, i.e., 1. a carbo-reduction process, 2. a glass production/recycling furnace, 3. an aluminothermic reactor for the production of a ferroniobium alloy, and 4. a titanium purification unit. Moreover, the relevance of key fundamental thermodynamic concepts is discussed through the modeling of these unit operations. All the thermodynamic simulations presented in this work were performed using FactSage, a metallurgy-specialized thermochemical package widely employed in both academia and industry.

Reverse osmosis water purification and brine valorization in a Tunisian hemodialysis center

ABSTRACT The technical–economic analysis of the hemodialysis water purification process, which uses reverse osmosis with sand, softeners, and granular-activated carbon as pretreatment steps, shows that the permeate conductivity exceeds 25 µS cm−1 at 25°C due to softeners failure and that the cost of cubic meter of water produced is 2.4 €. The purification unit generated brine with a conductivity above 5 mS.cm−1 and it is discharged into the sewer. Several brine valorizations are proposed; brine recycling and simulation with IMS design software reveal that it is possible to recycle 0.2 m3.h−1 of brine and achieve 83% conversion rate with a good quality of permeate. The residual of the first reverse osmosis brine is diluted by the second reverse osmosis permeate and is to be used for toilet flushing, landscape irrigation, and sterilization steam production.